Different expression levels of the TAP peptide transporter lead to recognition of different antigenic peptides by tumor-specific CTL

Decreased antigenicity of cancer cells is a major problem in tumor immunology. This is often acquired by an expression defect in the TAP. However, it has been reported that certain murine Ags appear on the target cell surface upon impairment of TAP expression. In this study, we identified a human CTL epitope belonging to this Ag category. This epitope is derived from preprocalcitonin (ppCT) signal peptide and is generated within the endoplasmic reticulum by signal peptidase and signal peptide peptidase. Lung cancer cells bearing this antigenic peptide displayed low levels of TAP, but restoration of their expression by IFN-γ treatment or TAP1 and TAP2 gene transfer abrogated ppCT Ag presentation. In contrast, TAP upregulation in the same tumor cells increased their recognition by proteasome/TAP-dependent peptide-specific CTLs. Thus, to our knowledge, ppCT(16-25) is the first human tumor epitope whose surface expression requires loss or downregulation of TAP. Lung tumors frequently display low levels of TAP molecules and might thus be ignored by the immune system. Our results suggest that emerging signal peptidase-generated peptides represent alternative T cell targets, which permit CTLs to destroy TAP-impaired tumors and thus overcome tumor escape from CD8(+) T cell immunity.     

Differentiation of Fanconi anemia and aplastic anemia using mitomycin C test in Tunisia

Fanconi anemia (FA) is a recessive chromosomal instability syndrome that is clinically characterized by multiple symptoms. Chromosome breakage hypersensitivity to alkylating agents is the gold standard test for FA diagnosis. In this study, we provide a detailed laboratory protocol for accurate assessment of FA diagnosis based on mitomycin C (MMC) test. Induced chromosomal breakage study was successful in 171 out of 205 aplastic anemia (AA) patients. According to the sensitivity of MMC at 50 ng/ml, 38 patients (22.22%) were diagnosed as affected and 132 patients (77.17%) as unaffected. Somatic mosaicism was suspected in an 11-year-old patient with a FA phenotype. Twenty-six siblings of FA patients were also evaluated and five of them (19.23%) were diagnosed as FA. From this study, a standard protocol for diagnosis of FA was developed. It is routinely used as a diagnostic test of FA in Tunisia.     

Bacillus cereus adhesion: Real time investigation of the effect on the chemistry of industrial stainless steel

The initial microorganism adhesion on substrate is an important step for the biofilm formation. The surface properties of the stainless steel and B. cereus were characterized by the sessile drop technique. Moreover, the physicochemical properties of surface adhesion and the impact of bio adhesion to the stainless steel were determined at different time of contact (2, 4, 7, 9 and 24 h). The results showed that the strain was hydrophilic (Giwi = 3.37 mJ/m²), whereas the substratum has hydrophobic character (Giwi = ?57.6 mJ/m²). Stainless steel surface presents a weak electron-donor character (γ^? = 4.1 mJ/m²) conversely to B. cereus that presents an important parameter (γ^? = 31.6 mJ/m²). The bio adhesion was investigated at different time of contact. The data analysis after 2 h, confirmed the adhesion of B. cereus with an amount of 10 cfu/cm² which increased to 1.210⁴ cfu/cm² after 24 h. Interestingly, despite the difference of hydropohbicity, the interaction between B. cereus and substratum was favored by the thermodynamic aspect of adhesion (ΔG_adhesion < 0). Interestingly, the study of the effect of B. cereus adhesion on the stainless steel has revealed that, the substratum becomes hydrophilic (θ° = 41.3, ΔGiwi = 39.6 mJ/m²) and highly electron donor (Γ^? = 52.9 mJ/m²) after 2 h of bio adhesion.     

Influence of three rates of salinity on okra plants (Abelmoschus esculentus L.) infected with root-knot nematode in vivo

A greenhouse experiment was carried-out to evaluate the effect of three rates of salinity as abiotic stress on okra plants (Abelmoschus esculentus) infected with the root-knot nematode (Meloidogyne incognita) as biotic stress. Plant lengths and weights were significantly (p?≤?0.05) reduced except root weight and there was a positive correlation between increasing the salinity concentration from 0.1 to 0.3% and increasing the rate of reduction in plant criteria. The number of J2 in soil, galls, and eggmasses were decreased linked to increased salinity rate as compared to nematode control treatment. However, peroxidase and catalase activities were significantly reduced linked to increasing the salinity concentration from 0.1 to 0.3%. There was no significant difference between total phenols at all treatments. Meanwhile, there was no significant improvement in N, P, and K contents whereas photosynthetic pigments (a, b) and carotene were significantly (p?≤?0.05) reduced by nematode infection and increasing the salinity rate from 0.1 to 0.3%.     

Relation between leptin and estradiol levels in Egyptian lactating Arab mares during foaling heat

Sixteen Arab lactating mares belonging to Al-Zahraa Arab Horse Stud underwent two ultrasound examinations at 3 weeks interval starting from the day of demonstration of foaling heat. In addition, daily blood samples were collected from parturition until after exhibiting first postpartum estrus (day 11) with daily observation of estrous signs. Both leptin and estradiol hormones were assayed. Mean day of foaling heat was 8.9 ± 0.9 day. Most mares came in foaling heat during days 9 and 10 had high conception rate compared to those who came in estrus earlier or later. Estradiol levels were high after day of foaling then decrease after expression of foaling heat. But leptin levels increase from day 8 to day 10 compared to other days before and after the first ovulation. A significant positive correlation was found between estradiol and leptin (r = 0.58, p < 0.025). The positive correlation between leptin and estradiol led us to suggest that leptin hormone plays an important role in ovulation of the first postpartum estrus in mares.     

Caulobacter crescentus synthesizes an S-layer-editing metalloprotease possessing a domain sharing sequence similarity with its paracrystalline S-layer protein

Strains of Caulobacter crescentus elaborate an S-layer, a two-dimensional protein latticework which covers the cell surface. The S-layer protein (RsaA) is secreted by a type I mechanism (relying on a C-terminal signal) and is unusual among type I secreted proteins because high levels of protein are produced continuously. In efforts to adapt the S-layer for display of foreign peptides and proteins, we noted a proteolytic activity that affected S-layer monomers with foreign inserts. The cleavage was precise, resulting in fragments with an unambiguous N-terminal sequence. We developed an assay to screen for loss of this activity (i.e., presentation of foreign peptides without degradation), using transposon and traditional mutagenesis. A metalloprotease gene designated sap (S-layer-associated protease) was identified which could complement the protease-negative mutants. The N-terminal half of Sap possessed significant similarity to other type I secreted proteases (e.g., alkaline protease of Pseudomonas aeruginosa), including the characteristic RTX repeat sequences, but the C-terminal half which normally includes the type I secretion signal exhibited no such similarity. Instead, there was a region of significant similarity to the N-terminal region of RsaA. We hypothesize that Sap evolved by combining the catalytic portion of a type I secreted protease with an S-layer-like protein, perhaps to associate with nascent S-layer monomers to "scan" for modifications.