Polymorphisms in human DNA repair genes and head and neck squamous cell carcinoma

Genetic polymorphisms in some DNA repair proteins are associated with a number of malignant transformations like head and neck squamous cell carcinoma (HNSCC). Xeroderma pigmentosum group D (XPD) and X-ray repair cross-complementing proteins 1 (XRCC1) and 3 (XRCC3) genes are involved in DNA repair and were found to be associated with HNSCC in numerous studies. To establish our overall understanding of possible relationships between DNA repair gene polymorphisms and development of HNSCC, we surveyed the literature on epidemiological studies that assessed potential associations with HNSCC risk in terms of gene–environment interactions, genotype-induced functional defects in enzyme activity and/or protein expression, and the influence of ethnic origin on these associations. We conclude that large, well-designed studies of common polymorphisms in DNA repair genes are needed. Such studies may benefit from analysis of multiple genes or polymorphisms and from the consideration of relevant exposures that may influence the likelihood of HNSCC when DNA repair capacity is reduced.     

Bayesian and Phylogenic Approaches for Studying Relationships among Table Olive Cultivars

To enhance table olive tree authentication, relationship, and productivity, we consider the analysis of 18 worldwide table olive cultivars (Olea europaea L.) based on morphological, biological, and physicochemical markers analyzed by bioinformatic and biostatistic tools. Accordingly, we assess the relationships between the studied varieties, on the one hand, and the potential productivity–quantitative parameter links on the other hand. The bioinformatic analysis based on the graphical representation of the matrix of Euclidean distances, the principal components analysis, unweighted pair group method with arithmetic mean, and principal coordinate analysis (PCoA) revealed three major clusters which were not correlated with the geographic origin. The statistical analysis based on Kendall’s and Spearman correlation coefficients suggests two highly significant associations with both fruit color and pollinization and the productivity character. These results are confirmed by the multiple linear regression prediction models. In fact, based on the coefficient of determination (R ²) value, the best model demonstrated the power of the pollinization on the tree productivity (R ² = 0.846). Moreover, the derived directed acyclic graph showed that only two direct influences are detected: effect of tolerance on fruit and stone symmetry on side and effect of tolerance on stone form and oil content on the other side. This work provides better understanding of the diversity available in worldwide table olive cultivars and supplies an important contribution for olive breeding and authenticity.     

Effect of subchronic exposure to tetradifon on bone remodelling and metabolism in female rat

This study investigates the effect of subchronic exposure to tetradifon, an organochlorine pesticide with an oestrogen-like structure, in female rat. A single cumulative dose of 2430 mg/kg BW was administrated orally for 12 female rats of 190 g BW. Twelve non-treated additional rats have served as controls. Animals were sacrificed after 6 and 12 weeks of treatment. We studied bone remodelling through histomorphometry and scanning electron microscopy (SEM) analyses. The serum and the right femora were used to determine phosphatase alkaline (AlkP) and/or calcium and phosphorus content. No sign of toxicity was observed until the end of the experiment. The SEM results revealed no structural alteration of the treated animal bone tissue. However, in both treated groups, we have noted an increase in the trabecular distance and a heterogeneous aspect of the endosteum that could be explained by bone-remodelling disturbance, with relative delay of ossification. Following histomorphomotric analysis, these results were coupled with significant increases in Tb.Th and OS/BS. Elsewhere, tetradifon intoxication increased significant serum AlkP level in the group treated for 12 weeks, which could be explained by an osteoblastic hyperactivity. Tetradifon intoxication decreased significantly bone calcium end phosphorus contents. Tetradifon seems not to exert major effects on bone remodelling. However, the osteoblastic hyperactivity could be explained by the oestrogen-like activity of tetradifon and its fatty metabolism. In fact, oestrogen inhibits bone remodelling, and enhances bone formation, which could result in an increase of the osteoid surface and explain the relative delay of ossification.     

Charge clusters signatures in prokaryotic proteomes: Temperature-dependence and distribution

The identification and the screening of Charged Clusters (CCs) residues in proteins is a key analysis to assess any quantitative structure-function correlation in proteins. Here, we present a proteome wide scan for the occurrence of (CCs) in 99292 proteins using a new tool. Finding Clusters Charge in Protein Sequences Program (FCCP). The FCCP has been employed to search CCs in 35 prokaryotic proteomes (7 Psychrophiles, 10 Mesophiles, 9 thermophiles and for 9 hyperthermophiles). A new repository of 855 CC has been created. Results showed that the mapped proteins containing positive and negative charge clusters are mostly transmembrane proteins while the conserved CCs within the same proteome are transposases or involved in DNA binding and integration. Interestingly, the negative charged cluster was associated to bacteria growth's temperature (p=0.002) acting as proteins' core signature. Taken together the various results provide a consistent picture of these screened CCs in terms of its potentials functional roles.     

Variation of steroid concentrations during the reproductive cycle of the clam Ruditapes decussatus: a one year study in the gulf of Gabès area

Progesterone, testosterone and estradiol-17beta were measured by radio-immunoassay (RIA) in the gonads of the clam Ruditapes decussatus. The reproductive cycle was also investigated. Our study covered a period of one year, from September 2003 to August 2004. The chosen site "Kerkennah", located out of industrial effluents, belongs to the gulf of Gabès area (Tunisia). Steroids varied from 178 to 2459 pg g(-1) wet mass for progesterone, from 40 to 326 pg g(-1) wet mass for testosterone and from 10 to 235 pg g(-1) wet mass for estradiol-17beta in females. However in males, these steroids ranged from 304 to 2303 pg g(-1) wet mass for progesterone, from 81 to 381 pg g(-1) wet mass for testosterone and from 48 to 168 pg g(-1) wet mass for estradiol-17beta. The reproductive cycle of R. decussatus, investigated by histological examination of gonadic sections, showed that gametogenesis occurred from April to February in males and from April to November in females. Progesterone and testosterone increased at the end of gametogenesis in both sexes. The highest estradiol-17beta was recorded at the beginning of vitellogenesis in females. Fluctuations in the levels of sex steroids during the reproductive cycle suggest their possible role as endogenous modulators of gametogenesis in R. decussatus. Although this species is considered as gonochoristic, 0.83% of hermaphrodites were observed.     

Muscle activation of the elbow flexor and extensor muscles during self-resistance exercises: comparison of unilateral maximal cocontraction and bilateral self-resistance

Muscle activation during self-resistance exercises was studied in 18 subjects performing (a) maximal unilateral isometric cocontractions of flexor and extensor muscles of the right elbow (UNI); (b) bilateral exercises consisting of maximal isometric extensions of the right elbow against the left elbow flexors (BiExt) and maximal isometric flexion of the right elbow against the left elbow extensors (BiFlex). Force production by the biceps brachii (BB), brachioradialis (BR), and triceps brachii (TB) during UNI, BiFlex, and BiExt were estimated by comparing the integrated surface electromyograms (iEMG) of BB, BR, and TB during UNI, BiExt, and BiFlex with the individual iEMG-force relationship determined from isometric contractions at 30, 60, and 100% maximal voluntary contraction during elbow flexion (MVCflex) or extension (MVCext) against a force transducer. During BiFlex for BB or BR and BiExt for TB, the values (mean ± SE) of BB-iEMG, BR-iEMG, and TB-iEMG were 74.0 ± 4.5, 76.6 ± 5.7, and 84.4 ± 4.5% iEMG at MVC (% iEMGmax). The forces were 86.0 ± 3.7% TB-Forcemax during BiExt, 74.1 ± 3.6% BB-Forcemax and 71.8 ± 4.0% BR-Forcemax during BiFlex. During UNI, BB-iEMG, BR-iEMG, and TB-iEMG were 59.9 ± 4.6, 53.4 ± 4.0, and 66.3 ± 4.7% iEMGmax, respectively. The forces during UNI (70.4 ± 4.0% TB-Forcemax, 60.4 ± 4.3% BB-Forcemax, and 49.2 ± 3.1% BR-Forcemax) were significantly lower than those during bilateral exercises. A 2-way analysis of variance (Muscle × Exercise) indicated that the effects of Muscle and Exercise upon % iEMGmax were significant (p < 0.05; p < 0.001, respectively). In conclusion, bilateral opposition exercises should be more effective in developing strength than cocontraction exercises, which correspond to a moderate activation level even for weak agonist muscle groups.