Analysis of Two Polymorphic Repeats IVS3 Poly A and IVS10 CA in Tunisian Cystic Fibrosis Patients: Case–Control Study

Russian Journal of Genetics - The aim of this study was to determine a possible association of IVS3 poly A and IVS10 CA microsatellites with CF in case–control Tunisian groups and to compare...     

Comparative Assessment of SSR and AFLP Markers for Evaluation of Genetic Diversity and Conservation of Fig, <Emphasis Type="Italic">Ficus carica</Emphasis> L., Genetic Resources in Tunisia

This study characterises the genetic variability of fig, Ficus carica L., using simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) markers. It compares the efficiency and utility of the two techniques in detecting variation and establishing genetic relationships among Tunisian fig cultivars. Our results show that using both marker systems, the Tunisian fig germ plasm is characterised by having a large genetic diversity at the deoxyribonucleic acid level, as most of AFLP bands were detected and all SSR markers were polymorphic. In fact, 351 (342 polymorphic) and 57 (57 polymorphic) bands were detected using AFLP and SSR primers, respectively. SSR markers were the most polymorphic with an average polymorphic information content value of 0.94, while AFLP markers showed the highest effective multiplex ratio (56.9) and marker index (45.2). The effective marker index was recorded highest (4.19) for AFLP markers and lowest (0.70) for the SSR ones. Our results demonstrate that (1) independent as well as combined analyses of cluster analyses of SSR and AFLP fragments showed that cultivars are clustered independently from their geographical origin, horticultural classifications and tree sex; (2) the analysis of molecular variance allowed the partitioning of genetic variation within and among fig groups and showed greater variation within groups and (3) AFLP and SSR markers datasets showed positive correlation. This study suggests the SSR and AFLP markers are suitable for diversity analysis and cultivars fingerprinting. An understanding of the genetic diversity and population structure of F. carica in Tunisia can also provide insight into the conservation and management of this species.     

Disturbance-dependent Yellow-legged Gull (Larus michahellis) predation on Larid chicks decreases with chick age

Predation is one of the key factors shaping the dynamics of animal populations. In birds, nest loss due to predation can be a significant cause of low reproductive success. Ground-nesting birds are among the bird groups most susceptible to predation, mainly because their nests are easily accessible to a broad suite of potential predators. For these birds, anthropogenic disturbances can generate changes in nest predation risk by altering their antipredator behaviour and also by altering the behaviour of the predator species, i.e. the predator becoming much more aware of predation opportunities due to frequent disturbances and/or motivated to repeat predation attempts when some are successful. To date, most previous studies investigating this have focused on a single effect, either predation or disturbance, on chick survival. It remains unknown how the risk of predation with and without disturbance varies with chick age. In this study, we used behavioural observations to assess how the interaction between predators and disturbance affects predation risk in chicks and how this interacts with chick age. Specifically, we investigated the effect of disturbance caused by humans and stray dogs on the predation of Slender-billed Gull Chroicocephalus genei chicks by Yellow-legged Gulls Larus michahellis, and whether this depended on the age of the chicks. Our results revealed that disturbance had a significant positive effect on predation measures of Slender-billed Gull chicks by Yellow-legged Gulls, but that this effect was mediated both by disturbance type and the age of chicks. Stray dogs entering the colony had a stronger disturbance effect on chicks than passing humans, increasing predation risk by Yellow-legged Gulls. Our results also showed that chick age interacts with disturbance type to determine the predation risk. This is probably mediated by chicks' capacity to escape predation by gathering in a single large crèche that runs into the water when disturbed. To preserve Slender-billed Gull colonies in one of its few remaining breeding sites in Tunisia, and as gulls tend to react even when the disturbance occurs relatively far from the colonies, it is crucial to (1) restrict human access to dikes and islets where large colonies breed and (2) construct artificial islets attractive to gulls and inaccessible to stray dogs.     

Myrtus communis berry color morphs: a comparative analysis of essential oils, fatty acids, phenolic compounds, and antioxidant activities

Extracts of mature dark blue and white berries from two Tunisian Myrtus communis morphs growing at the same site were assessed for their essential‐oil and fatty‐acid compositions, phenolic contents, and antioxidant activities. The GC and GC/MS analyses of the essential oils allowed the identification of 33 constituents. The oils from the dark blue fruits showed high percentages of α‐pinene (11.1%), linalool (11.6%), α‐terpineol (15.7%), methyl eugenol (6.2%), and geraniol (3.7%). Myrtenyl acetate (20.3%) was found to be the major compound in the oils from white berries. GC Analysis of the pericarp and seed fatty acids showed that the polyunsaturated fatty acids constituted the major fraction (54.3–78.1%). The highest percentages of linoleic acid (78.0%) and oleic acid (20.0%) were observed in the seeds and the pericarps of the white fruits, respectively. The total phenol, flavonoid, and flavonol contents and the concentration of the eight anthocyanins, identified by HPLC analysis, were significantly higher in the dark blue fruits. All extracts showed a substantial antioxidant activity, assessed by the free radical‐scavenging activity and the ferric reducing power, with the dark blue fruit extracts being more effective.     

Endothelium-dependent vascular relaxation induced by Globularia alypum extract is mediated by EDHF in perfused rat mesenteric arterial bed

The vasodilatory effect of Globularia alypum L. (GA) extract was evaluated in rat mesenteric arterial bed pre-contracted by continuous infusion of phenylephrine (2-4 ng/mL). Bolus injections of GA elicited dose-response vasodilation, which was abolished after endothelium removal. Addition of a nitric oxide synthase inhibitor, N(G)-nitro-l-arginine methyl ester (100 μmol/L), alone or in the presence of a cyclooxygenase inhibitor, indomethacin (10 μmol/L), did not significantly affect the vasodilation of the mesenteric arterial bed in response to GA extract. These results suggest that GA-induced vasodilation is endothelium dependent but nitric oxide and prostacyclin independent. In the presence of high K(+) (60 mmol/L), the GA vasodilatory effect was completely abolished, suggesting that the vasodilation effect is mediated by hyperpolarization of the vascular cells. Also, pre-treatment with atropine (a muscarinic receptors antagonist) antagonized the GA-induced vasodilation, suggesting that the vasodilatory effect is mainly mediated by the endothelium-derived hyperpolarizing factor through activation of endothelial muscarinic receptors.     

A higher-order entity formed by the flexible assembly of RAP1 with TRF2

Telomere integrity is essential to maintain genome stability, and telomeric dysfunctions are associated with cancer and aging pathologies. In human, the shelterin complex binds TTAGGG DNA repeats and provides capping to chromosome ends. Within shelterin, RAP1 is recruited through its interaction with TRF2, and TRF2 is required for telomere protection through a network of nucleic acid and protein interactions. RAP1 is one of the most conserved shelterin proteins although one unresolved question is how its interaction may influence TRF2 properties and regulate its capacity to bind multiple proteins. Through a combination of biochemical, biophysical and structural approaches, we unveiled a unique mode of assembly between RAP1 and TRF2. The complete interaction scheme between the full-length proteins involves a complex biphasic interaction of RAP1 that directly affects the binding properties of the assembly. These results reveal how a non-DNA binding protein can influence the properties of a DNA-binding partner by mutual conformational adjustments.     

Cloning and Sequencing of an Original Gene Encoding a Maltogenic Amylase from <Emphasis Type="Italic">Bacillus</Emphasis> sp. US149 Strain and Characterization of the Recombinant Activity

A gene encoding maltogenic amylase from acidic Bacillus sp. US149 (maUS149) was cloned, sequenced and over-expressed in Escherichia coli. The nucleotide sequence analysis revealed an open reading frame (ORF) of 1749 bp encoding a protein of 582 residues. The alignment of deduced amino acid sequence revealed a relatively low homology with the already reported maltogenic amylases. In fact, its highest identity, of only 60%, was found with the maltogenic amylase of Thermus sp. IM6501. The recombinant enzyme (MAUS149) was found to be intracellular and was purified to homogeneity from the cell crude extract with a yield of 23%. According to PAGE analysis, under reducing and non-reducing conditions, the recombinant enzyme has an apparent molecular weight of 135 kDa and is composed of two identical subunits of 67.5 kDa each. The maximum activity was obtained at 40°C and pH 6.5. MAUS149 could be classified as a maltogenic amylase since it produces mainly maltose from starch, maltose and glucose from β-cyclodextrin, and panose from pullulan.     

Antioxidative response of <Emphasis Type="Italic">Hordeum maritimum</Emphasis> L<Emphasis Type="Italic">.</Emphasis> to potassium deficiency

The objective of the present study was to determine the influence of potassium deprivation on the halophyte species Hordeum maritimum grown in hydroponics for 2 weeks. Treatments were with potassium (+K) or without potassium (−K). Growth, water status, mineral nutrition, parameters of oxidative stress [malondialdehyde (MDA), carbonyl groups (C=O), and hydrogen peroxide concentration (H₂O₂) contents], antioxidant enzyme activities [superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), guaiacol peroxidase (GPX, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate peroxidase (MDHAR, EC 1.6.5.4), dehydroascorbate peroxidase (DHAR, EC 1.8.5.1), and glutathione reductase (GR, EC 1.6.4.2)], and antioxidant molecules [ascorbate (ASC), and glutathione (GSH)] were determined. Results showed that the growth of vegetative organs decreased owing to potassium deficiency with roots (−36%) more affected than shoots (−12%). Water status was only diminished in roots (reduction of 24%). Potassium deprivation decreased potassium concentration in both organs, this decrease was more pronounced in roots (−81%) than in shoots (−55%). In contrast to carbonyl groups, MDA content increased owing to potassium deprivation. Except for CAT activity that remained unaffected; SOD, GPX, APX, GR, MDHAR, and DHAR activities were significantly increased. H₂O₂ concentration was negatively correlated with the activities of enzymes and the accumulation of non-enzymatic antioxidants implicated in its detoxification. In conclusion, a cooperative process between the antioxidant systems is important for the tolerance of H. maritimum to potassium deficiency.