Genomics reveals new landscapes for crop improvement

The sequencing of large and complex genomes of crop species, facilitated by new sequencing technologies and bioinformatic approaches, has provided new opportunities for crop improvement. Current challenges include understanding how genetic variation translates into phenotypic performance in the field.     

Inhibition of Leishmania (Leishmania) amazonensis and Rat Arginases by Green Tea EGCG, (+)-Catechin and (?)-Epicatechin: A Comparative Structural Analysis of Enzyme-Inhibitor Interactions

Epigallocatechin-3-gallate (EGCG), a dietary polyphenol (flavanol) from green tea, possesses leishmanicidal and antitrypanosomal activity. Mitochondrial damage was observed in Leishmania treated with EGCG, and it contributed to the lethal effect. However, the molecular target has not been defined. In this study, EGCG, (+)-catechin and (−)-epicatechin were tested against recombinant arginase from Leishmania amazonensis (ARG-L) and rat liver arginase (ARG-1). The compounds inhibit ARG-L and ARG-1 but are more active against the parasite enzyme. Enzyme kinetics reveal that EGCG is a mixed inhibitor of the ARG-L while (+)-catechin and (−)-epicatechin are competitive inhibitors. The most potent arginase inhibitor is (+)-catechin (IC₅₀ = 0.8 µM) followed by (−)-epicatechin (IC₅₀ = 1.8 µM), gallic acid (IC₅₀ = 2.2 µM) and EGCG (IC₅₀ = 3.8 µM). Docking analyses showed different modes of interaction of the compounds with the active sites of ARG-L and ARG-1. Due to the low IC₅₀ values obtained for ARG-L, flavanols can be used as a supplement for leishmaniasis treatment.     

Predictors of Beta-Blocker Intolerance and Mortality in Patients After Acute Coronary Syndrome

Purpose

To investigate the predictors of intolerance to beta-blockers treatment and the 6-month mortality in hospitalized patients with acute coronary syndrome (ACS).

Methods

This was a single-center, prospective, and longitudinal study including 370 consecutive ACS patients in Killip class I or II. BBs were prescribed according to international guidelines and withdrawn if intolerance occurred. The study was approved by the institutional ethics committee of our university. Statistics: the clinical parameters evaluated at admission, and the related intolerance to BBs and death at 6 months were analyzed using logistic regression (p<0.05)in PATIENTS.

Results

BB intolerance was observed in 84 patients and was associated with no prior use of statins (OR: 2.16, 95%CI: 1.26–3.69, p= 0.005) and Killip class II (OR: 2.5, 95%CI: 1.30-4.75, p=0.004) in the model adjusted for age, sex, blood pressure, and renal function. There was no association with ST-segment alteration or left anterior descending coronary artery plaque. Intolerance to BB was associated with the greatest risk of death (OR: 4.5, 95%CI: 2.15–9.40, p<0.001).

Conclusions

After ACS, intolerance to BBs in the first 48 h of admission was associated to non previous use of statin and Killip class II and had a high risk of death within 6 months.     

Proteomic Profiling of Burkholderia cenocepacia Clonal Isolates with Different Virulence Potential Retrieved from a Cystic Fibrosis Patient during Chronic Lung Infection

Respiratory infections with Burkholderia cepacia complex (Bcc) bacteria in cystic fibrosis (CF) are associated with a worse prognosis and increased risk of death. In this work, we assessed the virulence potential of three B. cenocepacia clonal isolates obtained from a CF patient between the onset of infection (isolate IST439) and before death with cepacia syndrome 3.5 years later (isolate IST4113 followed by IST4134), based on their ability to invade epithelial cells and compromise epithelial monolayer integrity. The two clonal isolates retrieved during late-stage disease were significantly more virulent than IST439. Proteomic profiling by 2-D DIGE of the last isolate recovered before the patient’s death, IST4134, and clonal isolate IST439, was performed and compared with a prior analysis of IST4113 vs. IST439. The cytoplasmic and membrane-associated enriched fractions were examined and 52 proteins were found to be similarly altered in the two last isolates compared with IST439. These proteins are involved in metabolic functions, nucleotide synthesis, translation and protein folding, cell envelope biogenesis and iron homeostasis. Results are suggestive of the important role played by metabolic reprogramming in the virulence potential and persistence of B. cenocepacia, in particular regarding bacterial adaptation to microaerophilic conditions. Also, the content of the virulence determinant AidA was higher in the last 2 isolates. Significant levels of siderophores were found to be secreted by the three clonal isolates in an iron-depleted environment, but the two late isolates were more tolerant to low iron concentrations than IST439, consistent with the relative abundance of proteins involved in iron uptake.     

Membrane protein shaving with thermolysin can be used to evaluate topology predictors

Topology analysis of membrane proteins can be obtained by enzymatic shaving in combination with MS identification of peptides. Ideally, such analysis could provide quite detailed information about the membrane spanning regions. Here, we examine the ability of some shaving enzymes to provide large‐scale analysis of membrane proteome topologies. To compare different shaving enzymes, we first analyzed the detected peptides from two over‐expressed proteins. Second, we analyzed the peptides from non‐over‐expressed Escherichia coli membrane proteins with known structure to evaluate the shaving methods. Finally, the identified peptides were used to test the accuracy of a number of topology predictors. At the end we suggest that the usage of thermolysin, an enzyme working at the natural pH of the cell for membrane shaving, is superior because: (i) we detect a similar number of peptides and proteins using thermolysin and trypsin; (ii) thermolysin shaving can be run at a natural pH and (iii) the incubation time is quite short. (iv) Fewer detected peptides from thermolysin shaving originate from the transmembrane regions. Using thermolysin shaving we can also provide a clear separation between the best and the less accurate topology predictors, indicating that using data from shaving can provide valuable information when developing new topology predictors.     

Saponins from the roots of Chiococca alba and their in vitro anti-inflammatory activity

Five triterpenoidal saponins were isolated from the roots of Chiococca alba (L.) Hitchc. (Rubiaceae). Two of the saponins, chiococcasaponin III (3-O-β-d-glucopyranurosyl-3β-hydroxyolean-12,15-dien-28-oic acid 28-O-β-d-xylopyranosyl (1 → 4)-α-l-rhamnopyranosyl (1 → 2)-α-l-arabinopyranosyl ester) and chiococcasaponin IV (3-O-β-d-glucopyranurosyl-3β-hydroxyolean-12,15-dien-28-oic acid 28-O-α-l-rhamnopyranosyl (1 → 2)-α-l-arabinopyranosyl ester) were new and their structures were elucidated on the basis of extensive application of NMR techniques and high resolution electrospray mass spectrometry together with acid hydrolysis product analysis. As part of our investigations on the chemical profile and pharmacological activity of the roots of C. alba, we report the results of the evaluation of the activity of the saponin fractions against in vitro lipopolysaccharide-induced inflammation. The results found, strongly support the fractions I, III and IV as having anti-inflammatory properties.     

FAS/FASL Expression Profile as a Prognostic Marker in Squamous Cell Carcinoma of the Oral Cavity

FAS/FASL altered expression may cause tumor protecting immunomodulation, with a direct impact on patient prognosis. FAS expression was studied in 60 squamous cell carcinomas of the oral cavity. FAS expression did not show a significant association with tumor histopathological characteristics, but was significantly associated with lymph node positivity. FAS expression was significantly associated with disease specific death and negative FAS expression was an independent risk factor, increasing risk 4 times when compared to positive expression. When FAS and FASL expression results were combined, we were able to define high, intermediate and low risk profiles. Disease-free and disease-specific survival were significantly correlated with FAS/FASL expression profiles. The high risk category was an independent marker for earlier disease relapse and disease-specific death, with approximately 4- and 6-fold increased risk, respectively, when compared to the low risk profile. Risk profiles based on FAS/FASL expression showed that high risk was significantly associated with increased disease relapse and death, as well as shorter disease-free or disease-specific survival. This categorization, added to patient clinical data, may facilitate the choice of therapy, minimizing treatment failure and increasing disease control.