Staphylococcal protein a deletes B-1a and marginal zone B lymphocytes expressing human immunoglobulins: an immune evasion mechanism

Protein A (SpA) of Staphylococcus aureus is endowed with the capacity to interact with the H chain variable region (V(H)) of human Abs and to target >40% of B lymphocytes. To investigate whether this property represents a virulence factor and to determine the in vivo consequences of the confrontation of SpA with B lymphocytes, we used transgenic mice expressing fully human Abs. We found that administration of soluble SpA reduces B-1a lymphocytes of the peritoneal cavity and marginal zone B lymphocytes of the spleen, resulting in a markedly deficient type 2 humoral response. Single-cell PCR analysis and sequencing of the Ab V(H) gene repertoire revealed a significant reduction of V(H)3+ marginal zone B cells. Since the two B lymphocyte subsets targeted are involved in innate immune functions, our data suggest that crippling of humoral immunity by S. aureus represents an immune evasion mechanism that may aggravate recurrent infections.     

Purification and biochemical characterization of a detergent stable α-amylase from Pseudomonas stutzeri AS22

This study reports the purification and biochemical characterization of a novel maltotetraose-forming-α-amylase from Pseudomonas stutzeri AS22, designated PSA. The P. stutzeri α-amylase (PSA) was purified from the culture supernatant to homogeneity by Sepharose mono Q anion exchange chromatography, ultrafiltration and Sephadex G-100 gel filtration, with a 37.32-fold increase in specific activity, and 31% recovery. PSA showed a molecular weight of approximately 57 kDa by SDS-PAGE. The N-terminal amino acid sequence of the first 7 amino acids was DQAGKSP. This enzyme exhibited maximum activity at pH 8.0 and 55°C, performed stably over a broad range of pH 5.0 ≈ 12.0, but rapidly lost activity above 50°C. Both potato starch and Ca²⁺ ions have a protective effect on the thermal stability of PSA. The enzyme activity was inhibited by Hg²⁺, Mn²⁺, Cd²⁺, Cu²⁺, and Co²⁺, and enhanced by Ba²⁺. PSA belonged to the EDTA-sensitive α-amylase. The purified enzyme showed high stability towards surfactants (Tween 20, Tween 80 and Triton X-100), and oxidizing agents, such as sodium per borate and H₂O₂. In addition, PSA showed excellent compatibility with a wide range of commercial solid and liquid detergents at 30°C, suggesting potential application in the detergent industry. Maltotetraose was the specific end product obtained after hydrolysis of starch by the enzyme for an extended period of time, and was not further degraded.     

Salt-tolerant rhizobia isolated from a Tunisian oasis that are highly effective for symbiotic N2-fixation with Phaseolus vulgaris constitute a novel biovar (bv. mediterranense) of Sinorhizobium meliloti

Nodulation of common bean was explored in six oases in the south of Tunisia. Nineteen isolates were characterized by PCR–RFLP of 16S rDNA. Three species of rhizobia were identified, Rhizobium etli, Rhizobium gallicum and Sinorhizobium meliloti. The diversity of the symbiotic genes was then assessed by PCR–RFLP of nodC and nifH genes. The majority of the symbiotic genotypes were conserved between oases and other soils of the north of the country. Sinorhizobia isolated from bean were then compared with isolates from Medicago truncatula plants grown in the oases soils. All the nodC types except for nodC type p that was specific to common bean isolates were shared by both hosts. The four isolates with nodC type p induced N₂-fixing effective nodules on common bean but did not nodulate M. truncatula and Medicago sativa. The phylogenetic analysis of nifH and nodC genes showed that these isolates carry symbiotic genes different from those previously characterized among Medicago and bean symbionts, but closely related to those of S. fredii Spanish and Tunisian isolates effective in symbiosis with common bean but unable to nodulate soybean. The creation of a novel biovar shared by S. meliloti and S. fredii, bv. mediterranense, was proposed.     

Common polymorphisms of calpain-10 and the risk of polycystic ovary syndrome in Tunisian population: a case–control study

Recent studies have suggested that calpain-10 (CAPN10) gene polymorphisms play a role in the susceptibility to polycystic ovary syndrome (PCOS). The aim of the present study was to evaluate the possible association between three single nucleotide polymorphisms (SNPs) in CAPN10 gene: UCSNP-43 (rs3792267), UCSNP-19 (rs3842570), and UCSNP-63 (rs5030952) and PCOS in Tunisian cases and control women. Study subjects included 127 women with PCOS (mean age 29.8 ± 4.7 year) and 150 healthy women (mean age 33.5 ± 5.6 year). CAPN10 genotyping was carried-out by direct PCR and PCR–RFLP. Linkage disequilibrium pattern in the genomic region explored was determined by HAPLOVIEW 4.2 while reconstruction of haplotypes was done using PHASE 2.1. The phylogenetic distribution of haplotypes in the population was determined by ARLEQUIN 2.000. Six haplotypes were observed. None of SNPs associated with PCOS or its components while the haplotype H4 associated with the phenotype PCOS-obese (P < 0.025). Moreover the pair of haplotypes H1/H4 strongly associated with high blood-pressure (OR = 14.4, P < 0.012). This work confirms the association of CAPN10 gene with metabolic components in PCOS and highlights the role of haplotypes as strong and efficient genetic markers.     

Needs Assessment for Performance Improvement of Personnel in Charge of Epidemiological Surveillance in Morocco

Background

In line with the International Health Regulations (IHR 2005), the Morocco health surveillance system has been reinforced via infrastructure strengthening and decentralization in its regions. To plan for personnel capacity reinforcement actions, a national workforce needs assessment was conducted by the National Epidemiological Surveillance Service and the World Health Organization.

Methods

The assessment used an ad-hoc method comprising two stages: (1) A survey via a standardized electronic questionnaire, administered to all staff in regional and provincial surveillance teams. Data collected included demographics, basic qualification, complementary training, perceived training needs, and preferred training modalities. Individuals were asked to grade, on a nine-point scale, their perception of importance of a given list of tasks and of their capacity to perform them. The gap between perceptions was quantified and described. (2) Field visits to national, regional and provincial sites for direct observation and opinion gathering on broader issues such as motivators, barriers, and training needs from the local perspective.

Results

Questionnaire respondents were 122/158 agents at 78 surveillance units countrywide. Mean age was 43.6 years and job longevity 5.7 years. Only 53% (65/122) had epidemiology training, posted in 62% (48/78) of the structures. Self-assessed capacity varied by basic qualification and by structure level (regional vs. provincial). The gap between the importance granted to a task and the perceived capacity to perform it was sizable, showing an uneven distribution across competency domains, regions, surveillance level and staff''s basic qualification. From the opinions gathered, a problem of staff demotivation and high turnover emerged clearly.

Conclusions

Our method was successful in revealing specific details of the training needs countrywide. A national strategy is needed to ensure rational planning of training, personnel motivation and long-term sustainability. In terms of training, an innovative program should target the specific needs per group and per region.     

Preparation and use of media for protease-producing bacterial strains based on by-products from Cuttlefish (Sepia officinalis) and wastewaters from marine-products processing factories

Cuttlefish powder (CFP) from Sepia officinalis by-products was prepared and tested as a fermentation substrate for microbial growth and protease production by several species of bacteria: Bacillus licheniformis, Bacillus subtilis, Pseudomonas aeruginosa, Bacillus cereus BG1, and Vibrio parahaemolyticus. All microorganisms studied grew well and produced protease activity when cultivated in medium containing only CFP indicating that the strains can obtain their carbon and nitrogen source requirements directly from whole by-product proteins. Moreover, it was found that the addition to the cuttlefish medium of diluted fishery wastewaters (FWW), generated by marine-products processing factories, enhanced the production of protease. Maximum activity was obtained when cells were grown in cuttlefish media containing 5-times or 10-times diluted FWW. Five-times diluted FWW enhanced protease production by B. cereus BG1 and B. subtilis by 467% and 75% more than control media, respectively. The enhancement could have been due to the high organic content or high salts in FWW.As a result, cuttlefish by-products powder enriched with diluted FWW was found to be a suitable growth media for protease-producing strains. This new process, which converts underutilized wastes (liquid and solid) into more marketable and acceptable forms, coupled with protease production, can be an alternative way to the biological treatment of solid and liquid wastes generated by the cuttlefish processing industry.     

Stability of thermostable alkaline protease from Bacillus licheniformis RP1 in commercial solid laundry detergent formulations

The stability of crude extracellular protease produced by Bacillus licheniformis RP1, isolated from polluted water, in various solid laundry detergents was investigated. The enzyme had an optimum pH and temperature at pH 10.0–11.0 and 65–70 °C. Enzyme activity was inhibited by PMSF, suggesting that the preparation contains a serine-protease. The alkaline protease showed extreme stability towards non-ionic (5% Tween 20% and 5% Triton X-100) and anionic (0.5% SDS) surfactants, which retained 100% and above 73%, respectively, of its initial activity after preincubation 60 min at 40 °C.

The RP1 protease showed excellent stability and compatibility with a wide range of commercial solid detergents at temperatures from 40 to 50 °C, suggesting its further application in detergent industry. The enzyme retained 95% of its initial activity with Ariel followed by Axion (94%) then Dixan (93.5%) after preincubation 60 min at 40 °C in the presence of 7 mg/ml of detergents. In the presence of Nadhif and New Det, the enzyme retained about 83.5% of the original activity. The effects of additives such as maltodextrin, sucrose and PEG 4000 on the stability of the enzyme during spray-drying and during subsequent storage in New Det detergent were also examined. All additives tested enhanced stability of the enzyme.     

Effect of hexachlorobenzene on some male reproductive parameters in Meriones unguiculatus

Organochlorine pesticides are known to cause disturbances in many physiological functions. The effects of in vivo administered hexachlorobenzene (HCB) on the male testicular function were studied in Meriones unguiculatus. Three groups of sexually mature meriones were orally exposed to 1.6, 4, and 16 mg/kg of body weight in olive oil for 30 days. Morphological and morphometrical estimations were applied to quantify some structural constituents of the testes. Testicular weight was significantly decreased in all treated groups, while no change was noted in seminal vesicle weight. A decrease in the spermatozoid content of the seminiferous tube was noted and appeared correlated with a modification of the process of spermatogenesis. Spermatic activity in HCB-treated animals testes decreased significantly, particularly in the group treated with the higher dose (60+/-3.16% vs. 88+/-4.89% in controls). Plasma testosterone levels were decreased significantly in the groups treated with 4 and 16 mg[HCB]/kg BW (0.48+/-0.08 ng/ml and 0.54+/-0.07 ng/ml) comparatively to controls (1.08+/-0.1 ng/ml) p<0.01.     

Molecular Diagnostic and Prognostic Subtyping of Gliomas in Tunisian Population

It has become increasingly evident that morphologically similar gliomas may have distinct clinical phenotypes arising from diverse genetic signatures. To date, glial tumours from the Tunisian population have not been investigated. To address this, we correlated the clinico-pathology with molecular data of 110 gliomas by a combination of HM450K array, MLPA and TMA-IHC. PTEN loss and EGFR amplification were distributed in different glioma histological groups. However, 1p19q co-deletion and KIAA1549:BRAF fusion were, respectively, restricted to Oligodendroglioma and Pilocytic Astrocytoma. CDKN2A loss and EGFR overexpression were more common within high-grade gliomas. Furthermore, survival statistical correlations led us to identify Glioblastoma (GB) prognosis subtypes. In fact, significant lower overall survival (OS) was detected within GB that overexpressed EGFR and Cox2. In addition, IDH1R132H mutation seemed to provide a markedly survival advantage. Interestingly, the association of IDHR132H mutation and EGFR normal status, as well as the association of differentiation markers, defined GB subtypes with good prognosis. By contrast, poor survival GB subtypes were defined by the combination of PTEN loss with PDGFRa expression and/or EGFR amplification. Additionally, GB presenting p53-negative staining associated with CDKN2A loss or p21 positivity represented a subtype with short survival. Thus, distinct molecular subtypes with individualised prognosis were identified. Interestingly, we found a unique histone mutation in a poor survival young adult GB case. This tumour exceptionally associated the H3F3A G34R mutation and MYCN amplification as well as 1p36 loss and 10q loss. Furthermore, by exhibiting a remarkable methylation profile, it emphasised the oncogenic power of G34R mutation connecting gliomagenesis and chromatin regulation.     

Apoptose et ségrégation méiotique dans les spermatozoïdes d'hommes porteurs de translocations

Men with a chromosomal translocation produce a significant percentage of unbalanced spermatozoa. In order to determine a correlation between chromosomal anomalies and apoptosis in human sperm, we analysed DNA fragmentation and meiotic segregation in sperm from men with a (13;14) Robertsonian translocation. We studied sperm from 12 (13;14) translocation carriers and 9 proven fertile men with a normal karyotype. Meiotic segregation of chromosomes 13 and 14 was analysed using dual-colour fluorescencein situ hybridization with locus-specific probes for chromosomes 13 and 14. Apoptosis in spermatozoa was measured byin situ TUNEL assay. The meiotic segregation study showed a significantly increased frequency of unbalanced spermatozoa for chromosomes 13 and 14 in (13;14) carriers (15.9%) compared to the control population (1.3%) (p=0.00016). The study of apoptosis showed an increase of DNA fragmentation in (13;14) carriers (34.9%) compared to the control population (13.8%) (p=0.0036). This increased apoptosis was observed in spermatozoa presenting an increase of unbalanced chromosomal anomalies concerning chromosomes 13 and 14, but with a predominance of balanced spermatozoa compared to the theoretical risk of meiotic segregation. These results suggest that apoptosis could be involved as a regulatory mechanism to eliminate unbalanced chromosomal spermatozoa in men with a (13;14) Robertsonian translocation.