Importance of ferric chelate reductase activity and acidification capacity in root nodules of N2-fixing common bean (Phaseolus vulgaris L.) subjected to iron deficiency

Iron is an essential nutrient for plants, especially in symbiotic N₂-fixing legumes. Although abundant in the soil, iron is generally not available to plants as it is predominantly in an insoluble form (Fe^III) . Mono- and dicotyledonous plants, except Grarnineae, have developed morphological and physiological responses, notably an increase in rhizosphere acidification (H⁺-ATPase) and an enhanced plasma membrane ferric chelate reductase activity (Fe-CR) in the roots. However, studies on the physiological responses of root nodules are lacking. The present study was initiated to investigate the acidification capacity and Fe-CR activity of nodulated roots, and intact nodules, in two contrasting common bean varieties, Coco blanc sensitive to iron deficiency and Flamingo tolerant to iron deficiency. The discovery of an induction of H⁺-ATPase and Fe-CR activities in root nodules of commonbean under iron deficiency, suggests that these organs participate in improving iron availability for the contained bacteroids.     

The RIN2 syndrome: a new autosomal recessive connective tissue disorder caused by deficiency of Ras and Rab interactor 2 (RIN2)

Defects leading to impaired intracellular trafficking have recently been shown to play an important role in the pathogenesis of genodermatoses, such as the Ehlers–Danlos and the cutis laxa syndromes. A new genodermatosis, termed macrocephaly, alopecia, cutis laxa and scoliosis (MACS) syndrome has been described, resulting from a homozygous 1-bp deletion in RIN2. RIN2 encodes the Ras and Rab interactor 2, involved in the regulation of Rab5-mediated early endocytosis. We performed a clinical, ultrastructural and molecular study in a consanguineous Algerian family with three siblings affected by a distinctive autosomal recessive genodermatosis, reported in 2005 by Verloes et al. The most striking clinical features include progressive facial coarsening, gingival hypertrophy, severe scoliosis, sparse hair and skin and joint hyperlaxity. Ultrastructural studies of the skin revealed important abnormalities in the collagen fibril morphology, and fibroblasts exhibited a dilated endoplasmic reticulum and an abnormal Golgi apparatus with rarefied and dilated cisternae. Molecular analysis of RIN2 revealed a novel homozygous 2-bp deletion in all affected individuals. The c.1914_1915delGC mutation introduces a frameshift and creates a premature termination codon, leading to nonsense-mediated mRNA decay. These findings confirm that RIN2 defects are associated with a distinct genodermatosis and underscore the involvement of RIN2 and its associated pathways in the pathogenesis of connective tissue disorders. The current family displays considerable phenotypic overlap with MACS syndrome. However, our family shows a dermatological and ultrastructural phenotype belonging to the Ehlers–Danlos rather than the cutis laxa spectrum. Therefore, the MACS acronym is not entirely appropriate for the current family.     

A New Structure-based Classification of Gram-positive Bacteriocins

Bacteriocins are ribosomally-synthesized peptides or proteins produced by a wide range of bacteria. The antimicrobial activity of this group of natural substances against foodborne pathogenic and spoilage bacteria has raised considerable interest for their application in food preservation. Classifying these bacteriocins in well defined classes according to their biochemical properties is a major step towards characterizing these anti-infective peptides and understanding their mode of action. Actually, the chosen criteria for bacteriocins’ classification lack consistency and coherence. So, various classification schemes of bacteriocins resulted various levels of contradiction and sorting inefficiencies leading to bacteriocins belonging to more than one class at the same time and to a general lack of classification of many bacteriocins. Establishing a coherent and adequate classification scheme for these bacteriocins is sought after by several researchers in the field. It is not straightforward to formulate an efficient classification scheme that encompasses all of the existing bacteriocins. In the light of the structural data, here we revisit the previously proposed contradictory classification and we define new structure-based sequence fingerprints that support a subdivision of the bacteriocins into 12 groups. The paper lays down a resourceful and consistent classification approach that resulted in classifying more than 70% of bacteriocins known to date and with potential to identify distinct classes for the remaining unclassified bacteriocins. Identified groups are characterized by the presence of highly conserved short amino acid motifs. Furthermore, unclassified bacteriocins are expected to form an identified group when there will be sufficient sequences.     

The Physiological Mechanisms Underlying N₂-Fixing Common Bean (<i>Phaseolus vulgaris</i> L.) Tolerance to Iron Deficiency

Iron is an essential element for plants as well as all living organisms, functioning in various physiological and biochemical processes such as photosynthesis, respiration, DNA synthesis, and N₂ fixation. In the soil, Fe bioavailability is extremely low, especially under aerobic conditions and at high pH ranges. In contrast, plants with nodules on their roots that fix atmospheric nitrogen need much more iron. To highlight the physiological traits underlying the tolerance of N₂-fixing common bean to iron deficiency, two genotypes were hydroponically cultivated in a greenhouse: Coco nain (CN) and Coco blanc (CB). Plants were inoculated with an efficient strain of Rhizobium tropici, CIAT899, and received a nutrient solution added with 0 µM Fe (severe Fe deficiency, SFeD), 5 µM Fe (moderate Fe deficiency, MFeD) or 45 µM Fe (control, C). Several physiological parameters related to photosynthesis and symbiotic nitrogen fixation were then analyzed. Iron deficiency significantly reduced whole plant and nodule growth, chlorophyll biosynthesis, photosynthesis, leghemoglobin (LgHb), nitrogenase (N₂ase) activity, nitrogen, and Fe nutrition, with some genotypic differences. As compared to CB, CN maintained better Fe allocation to shoots and nodules, allowing it to preserve the integrity of its photosynthetic and symbiotic apparatus, thus maintaining the key functional traits of the plant metabolism (chlorophyll biosynthesis and photosynthesis in shoots, leghemoglobin accumulation, and nitrogenase activity in root nodules). Plant growth depends on photosynthesis, which needs to be supplied with sufficient iron and nitrogen. Fe deficiency stress index (FeD-SI) and Fe use efficiency (FeUE) are two physiological traits of tolerance that discriminated the studied genotypes.     

Breast cancer in young women in southern Tunisia: Anatomical study and clinical prognostic factors: About a series of 83 patients

Purpose

To define epidemiological, clinical, therapeutic and prognostic factors influencing survival of breast cancer in young women younger than 35 in southern Tunisia.

Material and methods

This is a retrospective study of 83 patients younger than 35 years and treated within tumors mammary committee of Sfax.

Results

The mean age was 31.7 years. T2 stage, high grade with positive node tumors were frequent. Breast surgery was performed for 73 patients. Chemotherapy was neo-adjuvant, adjuvant and palliative for respectively 10, 62 and 13 patients. Radiotherapy was delivered for 65 patients with curative intent and for 8 metastatic patients. Endocrine therapy was adjuvant in 38 patients and palliative in 6 cases. The overall survival (OS) at 5 years was 66.8%. Pejorative prognostic factors in uni-variate analysis were clinical T stage (T3, T4), and the number of involved lymph nodes.

Conclusion

Despite adequate treatment, the prognosis of breast cancer in young women remains worse. Early diagnosis is necessary to promote outcome.     

Affinity comparison of different THCA synthase to CBGA using modeling computational approaches

The Δ^9-Tetrahydrocannabinol (THCA) is the primary psychoactive compound of Cannabis Sativa. It is produced by Δ^1- Tetrahydrocannabinolic acid synthase (THCA) which catalyzes the oxidative cyclization of cannabigerolic acid (CBGA) the precursor of the THCA. In this study, we were interested by the three dimensional structure of THCA synthase protein. Generation of models were done by MODELLER v9.11 and homology modeling with Δ1-tetrahydrocannabinolic acid (THCA) synthase X ray structure (PDB code 3VTE) on the basis of sequences retrieved from GenBank. Procheck, Errat, and Verify 3D tools were used to verify the reliability of the six 3D models obtained, the overall quality factor and the Prosa Z-score were also used to check the quality of the six modeled proteins. The RMSDs for C-alpha atoms, main-chain atoms, side-chain atoms and all atoms between the modeled structures and the corresponding template ranged between 0.290 Å-1.252 Å, reflecting the good quality of the obtained models. Our study of the CBGA-THCA synthase docking demonstrated that the active site pocket was successfully recognized using computational approach. The interaction energy of CBGA computed in ‘fiber types’ proteins ranged between -4.1 95 kcal/mol and -5.95 kcal/mol whereas in the ‘drug type’ was about -7.02 kcal/mol to -7.16 kcal/mol, which maybe indicate the important role played by the interaction energy of CBGA in the determination of the THCA level in Cannabis Sativa L. varieties. Finally, we have proposed an experimental design in order to explore the binding energy source of ligand-enzyme in Cannabis Sativa and the production level of the THCA in the absence of any information regarding the correlation between the enzyme affinity and THCA level production. This report opens the doors to more studies predicting the binding site pocket with accuracy from the perspective of the protein affinity and THCA level produced in Cannabis Sativa.     

The Trehalose Pathway Regulates Mitochondrial Respiratory Chain Content through Hexokinase 2 and cAMP in Saccharomyces cerevisiae

In yeast, trehalose is synthesized by a multimeric enzymatic complex: TPS1 encodes trehalose 6-phosphate synthase, which belongs to a complex that is composed of at least three other subunits, including trehalose 6-phosphate phosphatase Tps2 and the redundant regulatory subunits Tps3 and Tsl1. The product of the TPS1 gene plays an essential role in the control of the glycolytic pathway by restricting the influx of glucose into glycolysis. In this paper, we investigated whether the trehalose synthesis pathway could be involved in the control of the other energy-generating pathway: oxidative phosphorylation. We show that the different mutants of the trehalose synthesis pathway (tps1Δ, tps2Δ, and tps1,2Δ) exhibit modulation in the amount of respiratory chains, in terms of cytochrome content and maximal respiratory activity. Furthermore, these variations in mitochondrial enzymatic content are positively linked to the intracellular concentration in cAMP that is modulated by Tps1p through hexokinase2. This is the first time that a pathway involved in sugar storage, i.e. trehalose, is shown to regulate the mitochondrial enzymatic content.The control of glycolysis in the yeast Saccharomyces cerevisiae has been extensively studied. First, allosteric regulation of the irreversible steps catalyzed by phosphofructokinase (1), pyruvate kinase (review in Ref. 2), and fructose-1,6-bisphosphatase (1) has been proposed, even though the overexpression of these key enzymes does not increase the glycolytic flux (3). Other mechanisms of control have been proposed such as futile cycle activity (4) and an inhibitory effect of ATP (5). Indeed, it seems likely that the regulation of glycolysis is a complex process involving different hierarchical events leading from gene expression to the metabolic fluxes via protein levels, enzyme activities, and metabolite effects (6, 7). Among these actors, the product of the TPS1 gene has been shown to play an essential role in the control of the glycolytic pathway by restricting the influx of glucose into glycolysis (8). TPS1 encodes trehalose 6-phosphate (Tre6P)³ synthase (9–12). This enzyme is part of a multimeric protein complex composed of at least three other subunits, i.e. Tre6P phosphatase encoded by TPS2 (13) and the redundant regulatory subunits Tps3 and Tsl1 (14).A particularly intriguing finding is that tps1Δ mutants are defective not only for Tre6P synthesis but also for growth on glucose or related rapidly fermented sugars (8, 11, 15). This may be explained by an uncontrolled influx of glucose into the glycolytic pathway. This phenomenon is characterized by hyperaccumulation of glucose 6-phosphate, fructose 6-phosphate, and fructose 1,6-bisphosphate (Fru1,6bP) (8, 16–18) and depletion of ATP, P_i, and all intermediates of glycolysis downstream of glyceraldehyde-3-phosphate dehydrogenase (19). Several mutations have been described that suppress the growth defect of tps1Δ mutants apparently by reducing sugar influx into glycolysis (16, 20) or by diverting the excess sugar phosphate into glycerol synthesis through overexpression of the GPD1-encoded NAD-dependent glycerol-3-phosphate dehydrogenase (17, 21). Reconstitution of ethanolic fermentation in permeabilized yeast spheroplasts indicated that in addition to Tre6P, the Tps1 protein itself also seems to play a role in restricting glucose influx into glycolysis (22).Whatever the mechanism by which the multimeric complex involved in trehalose synthesis controls glycolytic flux in yeast, such a regulation is associated with modification of the cellular content of sugar phosphates. Moreover, in a recent paper, we have shown that in yeast, low physiological concentrations of glucose 6-phosphate and fructose 6-phosphate slightly (20%) stimulate the respiratory flux and that this effect was strongly antagonized by Fru1,6bP (18). On the other hand, Fru1,6bP by itself is able to inhibit mitochondrial respiration only in mitochondria isolated from a Crabtree-positive strain. Taken together, these results indicate that besides the thermodynamic link between glycolysis and mitochondrial respiration (i.e. the cytosolic ATP/ADP and NADH/NAD+ ratio), a kinetic control of oxidative phosphorylation activity is exerted by the level of glycolytic sugar phosphates (18, 23). This raises the question of a possible direct or indirect regulation of oxidative phosphorylation by the trehalose synthesis pathway.